The present invention relates to casted concrete block manufacturing and, more particularly, to an apparatus for roughing blocks to give them a worn or rough appearance.
The concrete block casting industry is well developed and is highly automated in its process operations for manufacturing conventional rectangular blocks and the like. The casted blocks have a geometrically uniform rectangular prism configuration in which the surfaces thereof are substantially planar with adjacent surfaces delimited by sharp edges.
It has been known to treat the concrete blocks in order to get a more natural rough look. As antique stone blocks were known to have rounded edges and irregular shaped surfaces, systems have been provided in order to produce such effect on the concrete blocks. However, the equipment used in order to treat these blocks has been incompatible with the fully automated handling equipment used in the other operations of the concrete block producing process. Substantial amount of manual labor and high costs are inherent with the presently used block roughing systems.
For instance, a known method consists in disposing the casted blocks in large tumbling drums. These tumbling drums are rotated about their longitudinal axis in order for the concrete blocks to tumble therein and to collide in order to get damaged. This method, although producing a generally satisfying look, entails substantial costs due to unrepairable damages to concrete blocks. Some blocks are damaged to a point where they may no longer be used and are thus thrown away or recycled. Also, some concrete block patterns may contain blocks of different sizes and these must be stored, which is very time consuming. Also, if a particular one of the blocks in pattern is destroyed more than other blocks, then often the other blocks are no longer useful as a ratio of blocks must be kept. By its nature, the tumbling drum requires frequent repairs. Furthermore, the personnel used for these purposes must deal with a noisy environment due to the tumbling action, and injuries are frequent due to the hazardous operations and handling required thereby. It is difficult to maintain a stable labour force for this work.
U.S. Pat. No. 5,133,915, issued on Jul. 28, 1992 to Metten et al., discloses a surface upon which a plurality of concrete blocks are disposed in a spaced apart relationship. A roller brush translates over the surface of concrete blocks in a reciprocating manner, thereby stripping and roughing the surface of the concrete blocks. Although this method provides substantial advantages over the tumbling drum method described above, it requires that the concrete blocks are spaced apart in order for the sharp edges thereof to be treated. Otherwise, only the top surface would be abraded. Furthermore, the brush type roller provides a relatively uniform abrasion of the concrete blocks, which is not a desired result for use with paving blocks. Finally, as the concrete blocks are spaced apart, the brush can only strike them at a certain velocity in order not to displace them. If they are displaced, they may end up in abutment with one another, whereby only the top surfaces will be abraded, leaving the sharp edges of the block intact. These blocks are usually treated before concrete is cured.
It is a feature of the present invention to provide a concrete block roughing apparatus which substantially overcomes the disadvantages of the above mentioned prior art.
According to the above features, from a broad aspect, the present invention provides an apparatus for roughing surfaces of concrete casted blocks. The apparatus comprises a horizontally disposed surface roughing device having a plurality of impacting elements secured thereto and driven for impacting on a plurality of concrete casted blocks supported thereunder on a support table. The support table has a fiat support upper surface. A plurality of holes extends through the support table. A plurality of support pins are displaceable in associated ones of the boles and projectable above the upper surface at predetermined locations for supporting at least some of the plurality of said blocks tilted at a predetermined angle. Each of the pins is associated with a displaceable mechanism to axially displace the pins from a retracted position below the upper surface of the table to a projecting block tilting position above the upper surface, whereby to tilt selected ones of casted concrete blocks disposed on the support surface. Displacement means is provided to impart translationary displacement between the impacting elements and the support table to abrade the blocks by the impacting elements.